The present invention relates to continuously feeding a thin, flexible, wire-like object into a vessel, ladle, distributor, tundish or the like, filled with molten metal, the wire-like object being composed of or at least includes substances to serve as additives in the metal aiding in the process which the molten metal undergoes. The wire-like object envisioned here will in the following be called a wire for the sake of brevity. It is understood, however, that this wire is not necessarily made of metal.
It is known to introduce a covered or sheathed wire as defined into molten metal for purposes of providing additives to the metal. Such a method is, for example, disclosed and described in the German printed patent application No. 1,953,410. The allegation has been made that this particular method permits the controlled adding of an additive, particularly it has been alleged that the speed of adding can be controlled for purposes of introducing the additive deep into the melt. However, the penetration and immersion into deeper levels of the molten material is not controllable, for example, by means of just controlling the speed of feeding the wire into the vessel, simply because the wire material will melt close to the surface of the metal bath no matter how fast the wire is fed. The particular wire-additive, moreover, has to be enveloped in a cover being composed, for example, of a synthetic resin or the like, for purposes of containing the material constituting the "wire" prior to its introduction. That sheath will melt on contact with, possibly even earlier, the top layer of the molten metal. On the other hand, the particular cover must not remain in the molten metal during or even after further treatment thereof.
The German printed patent application No. 2,322,604 describes a method in which a wire-like object as defined is fed into a tundish or the like for purposes of feeding additives to the molten material treated in the equipment of which the tundish is a part. In this particular instance, one passes the wire through a guide tube in order to protect the wire particularly against attacks from the slag layer on top of the molten metal.
It is a decisive disadvantage of this particular method that the material of which the wire is composed will melt in the upper layers of the molten bath no matter what its configuration and speed. Therefore, introduction of these additives into deeper levels of the molten metal requires some kind of agitation of the bath such as stirring or creating turbulence in one form or another. Such agitation, however, poses its own specific disadvantages. One usually wants to have the slag accumulate on the top of the molten material; impurities are removed from the molten metal in that they are accumulated as part of the slag formation on top of the bath. If one now stirs and agitates the bath, these impurities are, at least in parts, flushed back again into the molten material and the purity of the raw melt, of course, deteriorates.
Another method of adding particular substances to molten metal includes, for example, the introduction of powder through a carrier gas. This fluidized powder is introduced by means of a pipe into the bottom portion of the vessel containing the molten metal. It is a decisive disadvantage of that particular method that one has to keep the carrier gas and the powder suspended therein, flowing in a continuing basis; otherwise the tube will fill up with molten metal. In view of the particular ferrostatic fluid pressure static conditions under which the pipe operates, one has very limited control over the amounts of additives that are being fed into a pool of molten metal. Moreover, it was found that the particular tube end easily clogs, terminating or at least severely impeding the flow of the powder plus the carrier gas fluid.